Ball type well safety valve apparatus

ABSTRACT

A well safety valve to be lowered into a well and be actuated from a location near the surface of the earth by an elongated flexible line or the like, with the valve unit including a ball valve containing a fluid passage and mounted pivotally to a carrier structure and actuable from a closed position to an open position by upward movement of the carrier structure and ball valve relative to an engaged seat and a body of the unit.

O United States Patent 1191 1111. 3,847,218

Boyadjietf et al. 5] Nov. 12, 1974 l l BALL TYPE WELL SAFETY VALVE 2,207,033 7/1940 Ton ey 166/72 APPARATUS 3332133 2131; E' S 122/35 n can 1 Inventors: e g Boyadjieff, wqodland 3.351.133 11/1967 cum, Jr. et 111 166/72 H1lls; Ben A. Otsap, Encmo, both of 3,675,718 7/1972 Kanady 166/224 A Calif.

I73] Assigncc: Varco International, Inc., Los Primary Examiner f pp Ange/es C lif Attorney, Agent, or F1rmW1ll1am P. Green [22] Filed: Oct. 29, 1973 [21] Appl. No.: 410,477 [57] ABSTRACT A well safety valve to be lowered into a well and be actuated from a location near the surface of the earth gfi g by an elongated flexible line or the like, with the valve [58] 166/72 224/A unit including a ball valve containing a fluid passage 0 care 3 and mounted pivotally to a carrier structure and actuable from a closed position to an open position by up- 56 R f Ct d ward movement of the carrier structure and ball valve 1 UNITE]; g z x r s QZTENTS relative to an engaged seat and a body of the unit. 1,911,323 5 1933 Otis 166/72 17 Claims 7 Drawing Figures i Em rw BALL TYPE WELL SAFETY VALVE APPARATUS CROSS REFERENCE TO RELATED APPLICATIONS Certain features of the apparatus disclosed in the present application have been shown and claimed in our copending application Ser. No. 252,808 filed May 12, 1972 on Remotely Operated Well Safety Valves, which was a continuation in part of our copending application Ser. No. 203,142 filed Nov. 30, 1971 on Remotely Operated Safety Valves now abandoned, and in copending application Ser. No. 410,418 filed Oct. 29, 1973 on Safety Valve for Wells.

BACKGROUND OF THE INVENTION This invention relates to improved safety apparatus for closing off the flow of production fluid upwardly within a well, either automatically upon development of an adverse condition in the well, or under the control of an operator when for any reason it may be desired to stop the fluid flow.

Our above identified prior application Ser. No. 252,808 shows a unique type of well safety valve arrangement including a valve unit which is located in fixed position deep within a well, and is then actuated between open and closed positions by longitudinal movement of a flexible line extending upwardly toward the surface of the earth. Desirably, the flexible line is maintained under tension when the valve is in its open condition, so that any release of that tensioned condition, either intentional or as a result of damage to a portion of the well equipment, will result in automatic closure of the valve, to thus protect the environment against damage by oil leakage. That prior application showed several types of valve units actuable in this manner, including certain forms of the invention in which a ball type valve was employed utilizing a ball having a passage extending through its interior and mounted for pivotal movement between an open position in which production fluid can flow upwardly through that passage and a closed position in which the ball blocks off upward flow of the fluid.

SUMMARY OF THE INVENTION The present invention relates to improvements in the above discussed general type of safety valve equipment, and particularly improvements in arrangements utilizing a pivotally movable ball valve as the main flow control element. More specifically, a purpose of the invention is to provide a ball valve which is actuable by a flexible line or the like in a very positive manner assuring effective actuation of the ball between its different conditions, with minimum complexity in the actuating mechanism, and with utmost reliability for effective functioning over a long period of time. To achieve this purpose, the present valves are designed so that upward pulling force exerted from the surface of the earth through the flexible line causes a corresponding upward movement of the ball valve element itself, and that upward movement of these two parts acts to pivot the ball valve element from its closed position to its opened position, and to simultaneously move the ball upwardly away from sealing engagement with an upwardly facing seat surface formed in the body of the device.

In order to facilitate return of the valve element downwardly to closed position upon release of the upward tensioning force on the flexible line or the like, the apparatus is preferably so designed that the pressure of the production fluid in the well is applied to a valve carrier structure in a manner at least partially compensating for the upward force exerted by the fluid against the ball valve itself. For this purpose, the ball valve may be mounted pivotally to the carrier structure for movement upwardly and downwardly therewith, and that carrier structure may then have an area exposed to the downward pressure of the production fluid in a manner causing that pressure to urge the carrier structure and therefore the ball downwardly relative to the body of the unit. The effective area against which this downward pressure is exerted by the production fluid should desirably be greater than the effective downwardly facing seating area of the ball valve element, so that the net overall effect of the pressure of the well fluid on the movable ball assembly is to urge the carrier structure and ball downwardly to their closed position. A spring or springs may be supplied for assisting or commencing this downward displacement, in which case at the very minimum the spring force in conjunction with the downward force exerted by the fluid pressure should exceed the upward force of the fluid pressure, though preferably as specified above the downward fluid force itself should exceed the upward fluid force irrespective of the presence of a supplementary spring force.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other features and objects of the invention will be better understood from the following detailed description of the typical embodiment illustrated in the accompanying drawings in which:

FIG. 1 represents a well containing safety valve apparatus constructed in accordance with the invention;

FIG. 2 is an enlarged fragmentary vertical section through certain portions of the apparatus of FIG. 1, and showing the main safety valve element in its open condition;

FIG. 3 is a further enlarged vertical axial section through the valve unit of FIG. 2, and showing the valve element in its closed position;

FIG. 4 is an enlarged vertical section taken primarily on line 44 of FIG. 2, but showing certain of the elements in elevation;

FIG. 4a shows the connector structure of the apparatus before a connection is made;

FIG. 5 shows the lower portion of the apparatus of FIG. 4, with the valve in its closed condition; and

FIG. 6 is an enlarged horizontal section taken on line 66 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows, somewhat diagramatically, a well 10 having a casing 11 containing a conventional string of production tubing 12 extending downwardly from an upper well head 13 at the surface of the earth to a production zone 14 deep within the well. Production fluid from the formation surrounding the production zone 14 flows upwardly through string 12 and through well head 13 for discharge to a storage tank 116 or an appropriate distribution line. The tubing is formed in the usual manner of a series of tubular sections or stands connected in an end to end series by internally threaded couplings 15. It is of course to be understood that the well may either be of the typically illustrated type drilled directly into the surface of the earth, or be an underwater well, drilled from a barge or ship floating on the surface of a body of water, with the well casing and its contents extending downwardly through the water to the floor of the ocean or other body of water, and then into the earth at that location.

The safety valve unit proper is designated generally by the number 17 in FIG. 1, and is set in fixed position within the lower portion of tubing string 12 by a landing and sealingunit represented at 18. Unit 18 may be constructed integrally with valve unit 17, or may be a separately formed attached conventional landing and sealing unit as illustrated, rigidly connected to the upper end of the valve unit 17 by a threaded connection 19 (FIG. 2). The safety valve is actuated and controlled by an elongated flexible line 20, preferably of the type commonly referred to as a wireline. This line or cable extends upwardly to the surface of the earth for control by a powered operating mechanism designated generally at 21. The line 20 may be any conventional or known type of flexible cable or the like, including elementsof this type formed of either a single wire or strand, or a number of wires or strands interwoven or wound together. 7

The landing and sealing unit 18 is typically and somewhat diagramatically illustrated as of the same conventional key-type" shown and described in our above identified copending applications. Specifically, this unit 18 may include a tubular body member 22 connected at its lower end to the upper end of body 23 of valve unit 17 by the previously mentioned threaded connection 19, with an annular seal ring 24 of rubber or other elastomeric material clamped between shoulders on elements 22 and 23 as seen in FIG. 2 for annular engagement with the inner surface of tubing 12 to form a fluid tight seal therewith preventing upward flow of fluid about the outside of elements 22 and 23 at the location of seal 24. Disposed about body 22, the landing and sealing'unit 18 includes a sleeve or mandrel 25 containing apertures through which a number of circularly spaced locking keys or dogs 26 project radially outwardly for interfitting reception within a mating locating groove or plurality of grooves 27 formed in a coacting locating or landing nipple 28 connected into tubing 12. As is conventional in this type of device, keys 26 may be spring pressed radially outwardly relative to sleeve 25 for automatic reception within the groove or grooves 27 when they-reach the location of the groove,

with the keys then being locked in their outer holding positions in conventional manner by predetermined manipulation of body 22 from the surface of the earth. For example, the keys may be locked in their outer positions by a rapid vertical jarring movement of body 22 serving to shear a connection between the body and sleeve 25 and thereby move a locking or camming portion of the body into a position behind or radially inwardly of the keys. After being set by this type motion, the keys thereafter positively lock sleeve 25 and body 22 against both upward and downward movement relative to section 28 of the tubing, to thereby positively retain the valve unit 17 in its FIG. 1 position in the lower portion of the tubing string. Any other type of conventional landing equipment may of course be substituted for the particular key-type device typically illustrated in FIG. 2, such as for example a type having slips designed to be forced outwardly against the tubing in frictional holding relation, or having lugs which are receivable between the ends of successive lengths of the tubing 12, or any other known or usable type of apparatus controllable from the surface of the earth for holding the valve unit 17 in a fixed vertical setting.

The actuating unit 21 located near the surface of the earth preferably takes the form of an annular piston and cylinder mechanism, to which the upper end of the flexible line 20 is connectible, and through which a central vertical passage 29 is formed for passing production fluid upwardly through the interior of this actuating unit. The cylinder 30 of the piston and cylinder mechanism 21 is an essentially tubular element having a vertical cylindrical internal surface 31, and contains a piston 32 which is movable upwardly and downwardly along the vertical axis 33 of the well. The piston 32 has an upper enlarged diameter portion 34 slidably received within and sealed by an O-ring 35 with respect to the inner cylindrical surface 31 of cylinder 30. An annular hydraulic cylinder chamber 36 is thus formed between the cylinder and piston, acting to force the piston upwardly relative to the cylinder in response to the injection of pressure fluid into the chamber 36. The lower end of chamber 36 is closed by provision of a reduced diameter portion 37 of the cylinder, having an internal surface 38 slidably engaging and receiving the lower reduced diameter portion 39 of the piston, and sealed with respect thereto by an annular O-ring 40. Pressure fluid is introduced into the lower end of cylinder chamber 36 through a small fluid inlet line 41, connecting into the cylinder chamber at 42.

The upper end of piston 32 carries a spider 43, which supports a tubular element 44 at a central location within the piston, so that the flexible line 20 may extend upwardly through this tubular portion 44 and be attached to an upper enlarged head element 45 shaped to serve as a fishing neck, for engagement with a fishing tool to pull the flexible line upwardly if and when desired. Upward movement of the piston acts to displace head element 44 and the connected flexible line upwardly, to open the valve unit 17 and maintain the flexible line under tension.

The piston and cylinder mechanism 21 is preferably suspended in the well from the well head 13, from which the usual main flow control valve assembly or Christmas Tree projects upwardly, the lower portion of this valve assembly being represented at 46 in FIG. 2. To suspend the actuating piston and cylinder mechanism from the well head, there is desirably provided between elements 13 and 46 an adapter flange or ring 47, suitably secured to the flanges of elements 13 and 46, and appropriately sealed with respect thereto as by rings represented at 48 and 49. The upper end of cylinder 30 may be connected threadedly at 50 to a short suspending tube 51, sealed with respect to the cylinder at 52 and 53, and annularly sealed with respect to flange 47 at two vertically spaced locations 54 and 55. One or more locking dogs 56 may be threadedly connected into element 47 for projection into an annular external groove 57 formed in part 51, to suspend that part and the connected piston and cylinder mechanism in the illustrated position within the well, Actuating pressure fluid may be supplied to the piston and cylinder mechanism through an inlet passage 58 communicating through small passages 59 and 60 in elements 51 priate source represented diagramatically at 62 in FIG.

1, under the control of a manually or automatically operable three way valve or other valve represented at 63, for selectively either applying pressure to or releasing pressure from the hydraulic cylinder chamber 36.

As indicated previously, the novelty of the present invention relates especially to the structure of the valve unit 17 located at the bottom of the well. Referring particularly to the right hand portion of FIG. 2, this unit 17 includes a ball valve element 64 which is mounted to a vertically movable carrier structure 65 for relative rotation about a horizontal axis 66 intersecting and disposed perpendicular to the main vertical axis 33 of the well and tool. Carrier structure 65 is actuable vertically by flexible line 20 through a landing weight 67 and equalizer valve assembly 68, which. will be described in greater detail at a later point.

The body 23 of unit 17 is tubular and centered about the mentioned vertical axis 33, and may be formed sectionally of an upper first section 69 connected at 19 to part 22, a second vertically intermediate section 70 threadedly connected at 71 to part 69 and appropriately sealed with respect thereto, and a lower section 72 connected at 73 to section 70. At approximately the location of threaded joint 71,'the upper section 69 has a reduced internal diameter portion 74 with an internal cylindrical surface 75 slidably engaging an external cylindrical surface 76 on part 65 and sealed with respect thereto by an annular ring 77. Downwardly beneath the lower end of section 69, the outer surface of part 76 may increase slightly in diameter at 78, and retain that diameter to the location of an enlarged diameter lower piston head portion 79 having an external cylindrical surface 80 slidably engaging an internal cylindrical surface 81 of the side wall of body part 70. Thus, the upper annular upwardly facing surface 82 of the piston head portion 79 of carrier part 65 defines the lower end of an annular fluid chamber 83 whose upper end is in communication with the production fluid at the outside of the tool body through apertures 84 formed in the side wall of body part 70. A compression spring 85 contained within this annular chamber 83 isin all conditions maintained under compression and acts in opposite directions against a lower end shoulder 86.0n part 69 and the upwardly facing surface 82 of part 65 to yieldingly urge part 65 downwardly toward the FIG. 3

closed valve position of the parts.

The ball carrier part 65 is tubular and hollow, to define an internal cylindrical surface 86 centered about axis 33 and forming an inner passage through which production fluid flows upwardly within part 65 for ultimate discharge from the interior of that part through one or more openings 87 formed in a top web portion 88 of part 65. This web portion 88 is in turn connected rigidly to a rod 89 extending upwardly into the interior of the equalizer valve assembly 68.

Projecting downwardly from and beyond the lower enlarged external diameter piston portion 79 of part 65, this part has two parallel downwardly projecting ball mounting ears or lugs 90, positioned at diametrically opposite locations with respect to the main vertical axis 33 of the tool, and carrying two aligned'pivot pins 91 extending into opposite sides of the ball valve element 64 and mounting that element for pivotal movement relative to the two cars about the previously mentioned horizontal axis 66.

The ball valve element 64 has an external surface 92 which is spherical about a center 93 located on axis 33. This spherical surface is truncated at opposite sides of the ball adjacent mounting lugs 90 to form two parallel vertical flats or planar surfaces 94 movably contacting and abutting against correspondingly planar inner surfaces 95 of the lugs 90. A cylindrical passage 96 extends through the ball in one direction (vertically in FIG. 2), and may have an internal diameter corresponding substantially to the diameter of internal surface 86 of part 65, and aligned vertically therewith, to form a continuation of the vertical fluid flow passage through the part 65. In the FIG. 2 position of ball;6.4, passage 96 is centered about the vertical axis 33 of the tool. When the ball is pivoted through 90 about-axis 66 to the position of FIGS. 3 and 5, passage 96 extends horizontally, and one of the imperforate externally spherical portions 97 of the ball faces downwardly for engagement with an annular valve seat element 98 to block off fluid flow upwardly through the device. The ball is pivoted automatically between its open and closed positions of FIGS. 4 and 5 by two pins 99 which are carried by body part 70 of the unit and project inwardly therefrom into a pair of recesses or notches 100 formed in opposite sides of ball element 64. These recesses 100 may be elongated radially with respect to axis 66, as seen in FIGS. 4 and 5, so that upon upward movement of part 65 and ball 64, the engagement of pins 99 within recesses 100 causes the ball to automatically pivot through 90 from itsFIG. 5 position to its FIG. 4 position. 1

The valve seat element 98 is a ring of preferably elastomeric material such as rubber received within an annular part 101 clamped between a shoulder 102 on part 70 and an upper end shoulder on part 72, and sealed with respect to part 70 by an elastomeric seal ring 103. Beneath valve element 6.4, there is provided a tubular part 104, slidably engaging and located by an inner cylindrical surface 105 of element 101, and sealedwith respect thereto by an elastomeric ring 106. The upper annular edge of part 104 annularly engages the bottom of ball 64 at 107, in a relation such that internal cylindrical surface 108 forms a lower continuation of passage 96 in valve element 64 and passage 86 in part 65, with all of these passages desirably being of the same diameter. A spring 109 yieldingly urges part 104 upwardly against ball 64, but with a force which is relatively light as compared with downward force of spring 85 In the FIG. 5 lower closed position of ball element 64, the downwardly facing spherical surface of portion 97 of the ball engages downwardly against seat element 98 annularly, with the periphery of the seat engaging portion of the ball surface being defined by a circular line extending around the edge of the engaged area at the diameter D of FIG. 5. In considering the areas against which the production fluid exerts pressure, it may be assumed that the effective area to which upward pressure is applied is this seating area of the valve, that is, the area lying within a circle having the diameter D in FIG. 5. The area against which downward force is exerted by the main well pressure is, on the other hand, equal to the sum of the effective areas or horizontal projections of the two transverse upwardly facing surfaces at 82 and 78 on part 65 (ignoring any pressure which may be exerted downwardly against the upper side of the ball valve). The relationships between these various areas to which the main well pressure is applied, and the spring forces of elements 85 and 109, are such that, upon release of the tensioning force on flexible line 20, the total force exerted downwardly on elements 64 and 65, including both fluid and spring force, is always greater than the upward force exerted thereagainst, so that these forces tend to urge part 65 and ball 64 downwardly toward the closed valve position. Preferably, the relationship between the fluid induced forces themselves, irrespective of any spring force, is such that the downward force exerted against surfaces 82 and 78 is at least about as great as, and optimally substantially greater than, the upward fluid induced force against the ball valve. Stated differently, it is desirable that the total effective area of the upwardly facing surfaces at 82 and 78, projected onto a horizontal plane, be at least about as great as, and preferably substantially greater than, the previously defined downwardly facing seating area of the ball. When the downward fluid force thus exceeds the upward fluid force, the valve is inherently self closing with complete reliability any time that the cable force is released even though spring 85 may be broken. Further, the very light upward force of spring 109 should be less than the net downward force exerted by the fluid, so that even if spring 85 but not spring 109 breaks, the valve will still be closed by the fluid.

. The landing weight 67 of FIG 1 is connected at its upper end to flexible line 20, and at its lower end carries a downwardly projecting vertical rod 1 10 which may be detachably connectible to the upper end of equalizer valve assembly 68 by an essentially conventional'quick disconnect connection 111 (FIGS. 2, 3, 4 andj4a). This connection 111 includes apart 112 disposed about the lower portion of rod 110 and forming a series of downwardly projecting circularly spaced spring fingers '1 13 whose lower enlargements 114 are receivable withina socket recess 115 formed in the upper chuck portion 116 of body 117 of the equalizer valve assembly. The part 112, rod 110 and weight 67 are not lowered into the well until after the valve unit 17 and landing unit 18 have been set therein. At that time, parts 110 and 112 are lowered into the well in a condition in which a lower camming enlargement 118 carried by rod 110 is located downwardly beneath the level of enlargements 114 on spring fingers 113, as seen in FIG. 3. With the parts in this condition, enlargements 1 14 can move downwardly into the socket recess 115, and then spring radially outwardly in that recess, and be retained in the FIG. 4 full line connecting position by upward movement of enlargement 118 relative to the fingers and to a position between and blocking inward movement of the fingers. Thereafter, the connection 111 secures the rod 110 to body 117 with sufficient strength to withstand forces applied by the flexible line in the FIG. 2 open position of valve 64, and unless and until the cable 20 is forceably pulled upwardly with excessive force sufficient to shear a pin 1 19 which initially extends through and is carried by rod 110 in the conditions of FIG. 3 and 4, but which upon exertion of an upward jarring force is sheared off to allow upward movement of rod and its enlargement 118 beyond the position of FIG. 4, to move enlargement 118 upwardly above the enlargements 114 of fingers 113, and thereby allow inward displacement of enlargements 114 for release from chuck socket recess 115.

The equalizer valve assembly 68 includes a tubular slide valve element 120, which slidably engages the inner cylindrical surface 121 of body part 69, and

which in the normal closed position of FIG. 3 to which it tends to return blocks fluid flow through one or more apertures 122 formed in the side wall of part 69. When the valve is open these apertures place the interiorof body part 69 in communication with its exterior, to apply the same pressure to the upper side of main valve element 64 as to its underside.

The body part 117 of equalizer valve assembly 68 is a vertically extending tubular part, which rigidly carries sleeve valve element 120, as by provision of a series of circularly spaced radially extending web elements 123 (FIG. 6) allowing upward flow of production fluid circularly therebetween. Internally, part 108 has a chamber 124 within which two upper and lower compression springs 125 and 126 are received above and beneath an upper radial flange portion 127 carried at the upper end of rod 89.

To discuss briefly the use and operation of the above described apparatus, assume first that the units 17 and 18 are lowered into the wellby an appropriate running tool, and that flexible line 20 and its connected parts are then lowered into the well and manipulated to connect the fingers 114 tightly into the socket recess of chuck unit 116. The upper end of the flexible line is then connected to part '45 above the tubular element 44 of unit 21, and fluid under pressure is applied to chamber 36 of unit 21 from fluid source 62. This pressure fluid actuates piston 32 upwardly, to apply tension to and displace flexible line 20 upwardly, and correspondingly move body 117 of the equalizer valve assembly 68'upwardly relative to part 89 and the elements connected thereto, against the tendency of spring 126 in the equalizer valve assembly. This initial movement of part 117 without rod 89 and the connected parts acts to displace slide valve element upwardly far enough to open communication through apertures 122 between the exterior and interior of the upper portion of the tool body. This equalizes the pressure above and beneath ball valve 64, so that upon further upward movement of the flexible line and connected part 117, rod 89 and the attached ball carrier element 65 and ball 64 move upwardly relative to body 23, from the closed valve position of FIGS. 3 and 5 to the open valve position of FIGS. 2 and 4. Pins 99 cause pivotal movement of the ball about axis 66 upon such upward movement, to thereby swing the ball to its open position of FIGS. 2 and 4 in which passage 96 in the ball is aligned with passages 86 and 108 to pass production fluid upwardly through the device toward the surface of the earth without obstruction at the location of the valve. Cable 20 retains the valve in this open position until the tensioned condition of the cable is in some way released, as by accidental breaking of the cable by earthquake forces or other adverse conditions, or by intentional or accidental release of the pressurized condition in chamber 42 of upper actuator unit 21. When this tensioned condition of the cable is released, spring 85 commences downward movement of part 65 and ball toward the closed condition of FIGS. 3 and 5. When the valve reaches closed condition, the downward force exerted against part 65 by the application of fluid pressure to surfaces 78 and 82 is greater than the upward force exerted by the production fluid against the underside of valve 64, as previously discussed in detail, so that the net effect of the well pressure against the vertically movable parts is to retain the valve in its closed position of engagement with seat element 98, until the valve is forceably pulled upwardly again by actuation of flexible line 20. During the downward movement of the valve and its carrier part 65, equalizer valve element 120 again closes the bleed passages 122.

The second spring 125 above head 127 on rod 89 of the equalizer valve assembly is provided to allow limited resiliently resisted downward displacement of part 117 relative to part 89 by a running too] during lowering of unit 17 into the well, to thereby allow opening of the equalizer valve 120 downwardly beyond apertures 122 in a manner permitting circulation of well fluid upwardly through the tool as the tool is lowered into the well.

While a certain specific embodiment of the present invention has been disclosed as typical, the invention is of course not limited to this particular form, but rather is applicable broadly to all such variations as fall within the scope of the appended claims.

We claim:

1. Inwell safety apparatus actuable by an elongated member extending downwardly into a well and movable longitudinally from a location near the surface of the earth: a safety valve unit to be located deep within the well and comprising a body structure having a passage through which production fluid flows upwardly, a ball valve in said body structure containing a passage through which said production fluid can flow, a valve carrier structure mounted for upward and downward movement in the body by said elongated member and to which the ball valve is connected for pivotal movement between an open position in which said passage in the ball valve extends vertically to pass said production fluid and a closed position in which said passage in the ball extends horizontally to block off upward fluid flow past the ball valve, meansfor pivoting said ball valve from said closed position tosaid open position in response to upward movement of said valve carrier structure, and an upwardly facing valve seat engageable with said ball valve about an unapertured region thereof in said closedv position of the ball valve.

2. A safety valve unitas recited in claim 1, in which said valve carrier structure has a portion exposed to the pressure of the production fluid in a relation tending to move said carrier structure downwardly and thereby at least partially compensate for upward force exerted by the said production fluid pressure against the ball valve.

3. A safety valve unit as recited in claim 1, including spring means yieldingly urging said valve carrier structure downwardly.

4. A safety valve unit as recited in claim 1, in which which upward pressure of the production fluid is exerted.

5. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to.

6. A safety valve unit as recited in claim 1, in which .said valve carrier structure has a first portion of relatively small external diameter and a larger portion of increased diameter defining an annular piston flange exposed at its upper side to the pressure of the production fluid communicated from the exterior of said body structure in a relation tending to move said valve carrier structure downwardly and thereby at least partially compensating for upward force exerted by said production fluid pressure against the ball valve.

7. A safety valve unit as recited in claim 1, in which said valve carrier structure has a first portion of relatively small external diameter and a larger portion of increased diameter defining an annular piston flange exposed at its upper side to the pressure of the production fluid communicated from the exterior of said body structure in a relation tending to move said valve carrier structure and ball valve downwardly by said pressure, there being a spring disposed about said smaller diameter portion of the valve carrierstructure and acting downwardly against said enlarged diameter piston portion thereof to urge the valve carrier structure downwardly. i

8. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure exerted by the production fluid and tneding to urge said valve carrier structure and ball valve downwardly and to the closed position of the valve by said pressure, there being spring means yieldingly urging said valve carrier structure downwardly, the force of said spring means and the downward force exerted by said production fluid against said valve car-' rier structure being great enough together toovercome upward force exerted-against said ball valve by production fluid at the underside of the ball valve.

9. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure of production fluid communicated thereto from the exterior of said body structure, said area having an effective size greater than the effective seating area of the ball valve so that the net effect of the pressure of the production fluid is to displace the valve carrier structure and ball valve downwardly against the upward force exerted by the production fluid at the underside of the valve.

10. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure of production fluid communicated thereto from the exterior of said body structure, said area having an effective size greater than the effective seating area of the ball valve so that the net effect of the pressure of the production fluid is to displace the valve carrier structure and ball valve downwardly against the upward force exerted by the production fluid at the underside of the valve, there being a compression spring disposed about a portion of said valve carrier structure and yieldingly urging it downwardly.

11. A safety valve unit as recited in claim 1, including a tubular part at the underside of said ball valve engageable upwardly thereagainst at a location radially inwardly of said valve seat, and means yieldingly urging said tubular part upwardly against the ball valve.

12. A safety valve unit as recited in claim 1, including equalizer valve means operable upon initial upward movement of said elongated element to open communication between the exterior of said body structure and its interior at a location above the ball valve.

13. A safety valve unit as recited in claim 1, in which said body structure is a vertically elongated tubular structure having a lower opening into which production fluid flows upwardly toward the ball valve, said valve carrier structure being tubular above said ball valve and having an upper portion of relatively small external diameter and a lower piston portion of increased external diameter slidably engaging and sealed with respect to a side wall of said body structure, said carrier structure having ears projecting downwardly at opposite sides of the ball valve and pivotally mounting the latter in turn about a generally horizontal axis, said side wall of said body structure containing aperture means communicating the production fluid pressure from the exterior of the body structure into an annular space radially between said side wall of the body structure and said carrier structure and above said piston portion of the carrier structure to apply downward force thereto.

14. A safety valve unit as recited in claim 13, in

which the effective area of said carrier structure against which downward force is exerted by said production fluid is greater than the effective downwardly facing area of said ball valve lying within the periphery of the portion of said seat engaged by the ball valve in closed position, so that the net effect of the production fluid pressure is to urge the carrier structure and ball valve downwardly.

15. A safety valve unit as recited in claim 14, including a compression spring received within said annular space between said side wall of the body structure and said carrier structure and yieldingly urging said piston portion of said carrier structure downwardly.

16. A safety valve unit as recited in claim 15, including a tubular part at the underside of said ball valve engageable upwardly thereagainst at a location radially inwardly of said valve seat and mounted for upward and downward movement, following the ball valve, and a spring about said tubular part yieldingly urging it upwardly against the ball valve.

17. A safety valve unit as recited in claim 16, including an equalizer valve assembly above said carrier structure connecting it to said elongated member and operable upon initial upward movement of the elongated member to open communication between the exterior and interior of an upper portion of said body structure above the ball valve. 

1. In well safety apparatus actuable by an elongated member extending downwardly into a well and movable longitudinally from a location near the surface of the earth: a safety valve unit to be located deep within the well and comprising a body structure having a passage through which production fluid flows upwardly, a ball valve in said body structure containing a passage through which said production fluid can flow, a valve carrier structure mounted for upward and downward movement in the body by said elongated member and to which the ball valve is connected for pivotal movement between an open position in which said passage in the ball valve extends vertically to pass said production fluid and a closed position in which said passage in the ball extends horizontally to block off upward fluid flow past the ball valve, means for pivoting said ball valve from said closed position to said open position in response to upward movement of said valve carrier structure, and an upwardly facing valve seat engageable with said ball valve about an unapertured region thereof in said closed position of the ball valve.
 2. A safety valve unit as recited in claim 1, in which said valve carrier structure has a portion exposed to the pressure of the production fluid in a relation tending to move said carrier structure downwardly and thereby at least partially compensate for upward force exerted by the said production fluid pressure against the ball valve.
 3. A safety valve unit as recited in claim 1, including spring means yieldingly urging said valve carrier structure downwardly.
 4. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure exerted by the productioN fluid and and tending to urge said valve carrier structure and ball valve downwardly and to the closed position of the valve by said pressure, said area being at least about as large as the effective area of the ball valve against which upward pressure of the production fluid is exerted.
 5. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure exerted by the production fluid and tending to urge said valve carrier structure and ball valve downwardly and to the closed position of the valve by said pressure, said area being larger than the effective area of the ball valve against which upward pressure of the production fluid is exerted so that the net effect of the pressure of the production fluid is to urge said carrier structure and ball valve downwardly.
 6. A safety valve unit as recited in claim 1, in which said valve carrier structure has a first portion of relatively small external diameter and a larger portion of increased diameter defining an annular piston flange exposed at its upper side to the pressure of the production fluid communicated from the exterior of said body structure in a relation tending to move said valve carrier structure downwardly and thereby at least partially compensating for upward force exerted by said production fluid pressure against the ball valve.
 7. A safety valve unit as recited in claim 1, in which said valve carrier structure has a first portion of relatively small external diameter and a larger portion of increased diameter defining an annular piston flange exposed at its upper side to the pressure of the production fluid communicated from the exterior of said body structure in a relation tending to move said valve carrier structure and ball valve downwardly by said pressure, there being a spring disposed about said smaller diameter portion of the valve carrier structure and acting downwardly against said enlarged diameter piston portion thereof to urge the valve carrier structure downwardly.
 8. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure exerted by the production fluid and tneding to urge said valve carrier structure and ball valve downwardly and to the closed position of the valve by said pressure, there being spring means yieldingly urging said valve carrier structure downwardly, the force of said spring means and the downward force exerted by said production fluid against said valve carrier structure being great enough together to overcome upward force exerted against said ball valve by production fluid at the underside of the ball valve.
 9. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure of production fluid communicated thereto from the exterior of said body structure, said area having an effective size greater than the effective seating area of the ball valve so that the net effect of the pressure of the production fluid is to displace the valve carrier structure and ball valve downwardly against the upward force exerted by the production fluid at the underside of the valve.
 10. A safety valve unit as recited in claim 1, in which said valve carrier structure has an area exposed to downward pressure of production fluid communicated thereto from the exterior of said body structure, said area having an effective size greater than the effective seating area of the ball valve so that the net effect of the pressure of the production fluid is to displace the valve carrier structure and ball valve downwardly against the upward force exerted by the production fluid at the underside of the valve, there being a compression spring disposed about a portion of said valve carrier structure and yieldingly urging it downwardly.
 11. A safety valve unit as recited in claim 1, including a tubular part at the underside of said ball valve engageable upwardly thereagainst at a location radially inwardly of said valvE seat, and means yieldingly urging said tubular part upwardly against the ball valve.
 12. A safety valve unit as recited in claim 1, including equalizer valve means operable upon initial upward movement of said elongated element to open communication between the exterior of said body structure and its interior at a location above the ball valve.
 13. A safety valve unit as recited in claim 1, in which said body structure is a vertically elongated tubular structure having a lower opening into which production fluid flows upwardly toward the ball valve, said valve carrier structure being tubular above said ball valve and having an upper portion of relatively small external diameter and a lower piston portion of increased external diameter slidably engaging and sealed with respect to a side wall of said body structure, said carrier structure having ears projecting downwardly at opposite sides of the ball valve and pivotally mounting the latter in turn about a generally horizontal axis, said side wall of said body structure containing aperture means communicating the production fluid pressure from the exterior of the body structure into an annular space radially between said side wall of the body structure and said carrier structure and above said piston portion of the carrier structure to apply downward force thereto.
 14. A safety valve unit as recited in claim 13, in which the effective area of said carrier structure against which downward force is exerted by said production fluid is greater than the effective downwardly facing area of said ball valve lying within the periphery of the portion of said seat engaged by the ball valve in closed position, so that the net effect of the production fluid pressure is to urge the carrier structure and ball valve downwardly.
 15. A safety valve unit as recited in claim 14, including a compression spring received within said annular space between said side wall of the body structure and said carrier structure and yieldingly urging said piston portion of said carrier structure downwardly.
 16. A safety valve unit as recited in claim 15, including a tubular part at the underside of said ball valve engageable upwardly thereagainst at a location radially inwardly of said valve seat and mounted for upward and downward movement, following the ball valve, and a spring about said tubular part yieldingly urging it upwardly against the ball valve.
 17. A safety valve unit as recited in claim 16, including an equalizer valve assembly above said carrier structure connecting it to said elongated member and operable upon initial upward movement of the elongated member to open communication between the exterior and interior of an upper portion of said body structure above the ball valve. 